Metal soaps



1 encies as well as increasing oiliness.

' to 4 hours.

Patented Au 22, 1944 umTEos'rA'rEs PATENT "OFFICE l I I I v margins I'sstsra 'asaatgamma:

NoDrawing. Original application December 23, 1937,v Serial N0. 181,374.Divided and this applic'ation July 25, 1940, Serial No. 347,482

8 Claims. .(Cl. 260-448) This invention relates to lubricating oils forDiesel engines and is more particularly concerned with certain additionagents which when added to non-waxy lubricating oils greatly improvetheir properties.

It' is known that certain metallic soaps such as aluminum stearate andaluminum naphthenate improve the properties of lubricating oils forDiesel engines particularly with-respect to decreasing ring' stickingand varnish forming tend- A serious objection to the use of aluminumstearate for this'purpose is that it tends to-settle'out orgel uponstanding; An objection to'the use of aluminum naphthenate is that itrequires a temperature of 300 to 400 F. for solution in oil, and atthese temperatures color deterioration is inevitable and unavoidable.

It is desirable touse a metallic soap which'has all of the desirableproperties of these aluminum soapsbut which does notsettle outonfstanding and does notrequire temperatures for-solution high enough tocause color deterioration.

It has now been found that metallic soaps of acids obtained by theoxidation of sweater oil form extremely stablesolutions in non-waxylubricating oils and can be completely dissolved in the oily layer. Theaqueous layer contains the sodium soaps of the desired acids along witha small amount of unsaponiilable materials. The

unsaponiflable materials are then removed either I by naphtha extractionor by vaporization. Sulfuricacid is addedv to the sodium soaps toliberate the acids. The acids are then washed and the alkali (sodium,for example) soap is first preamounts of 0.1 to 3% in lubricating oil attemperatures between 175 and 200 F. at which no color deteriorationoccurs. The nature of these soaps and the method of preparing them willbe fully understood fromthe following description:

In dewaxing an oil containing pressable wax, the wax precipitated in theprocess is called crude slack wax. 'This contains varying quantities ofoil which is carrieddown with the wax.- The crude slack wax-is warmed tosweat out the oil.

The sweated wax is called crude scale wax, and

the oil obtained is called foots oil. The crude scale wax is subjectedto. another sweating operation and the oil so obtained is called sweateroil. It is this sweater oil obtained from the sweating of crude scalewax which is used as the starting material for the preparation of theacids desired in the present process.

Sweater oil is distinguished from crude scale wax by the fact that itcontains relatively much larger quantities of oil. 1

The sweater oil is oxidized with air or other gas containing free oxygenat a temperature between about 200 and 350 F. for a period of 2Variouscatalytic materials such as potassium permanganate, manganesestearate or soda ash may be used to promote the oxidation.

The reaction product is then saponified with caustic soda preferablycontaining some methyl alcohol. Thereafter, the mixture is thoroughlyagitated and the aqueous layer is separated from of the total acid andNo. 6 cut pared. The alkali soap, solution is then addedv to.

an' aluminum-s'ul fate solution, a slight excess of the' latter beingused. It will be understood that if other metallic soaps are desired,appropriate vsolutions of the metal salts will be used or the soaps maybe prepared by direct cooking of the acids with appropriate metallicoxides or hydroxides. r

. The aluminum soap is washed free of inorganic salts and may then bedried or may be incorporated directly in the oil without drying, inwhich 'latter case the moisture is removed from 'the compounded oil byblowing with air or an inert gas.

The metallic soap is'added to the oil in amounts of 0.1 to 3%. The oilis heated to a temperature between about 175 and 200 F. and the soapstirred into it. a

Various other metalsbesides aluminum may be used, such as calcium,nickel, cobalt, magnesium, manganese, chromium, tin, zinc, etc. Thesesoaps may be prepared as indicated above by adding the sodium soapto asolution of the metallic salt. -Other methods of preparation are, or

' 50 to 65% of the entire acid product.

The acid numbers and saponification numbers respectively areapproximately as follows:

- f Saponifl Acid No. cation number Crude acid product 161 238 No. 6 outl- 239 It is found that the soaps prepared from sweater oil acids aremarkedly diflerent in properties from those prepared from oxidized scalewax. For example, the acid and saponification numbers compare asfollows:

It is also found that the soaps of the No. 6 cut of oxidized scale waxas such are substantially insoluble in mineral oils whereas the soaps ofthe No. 6 cut of sweater oil acids are relatively much more soluble.

The following example illustrates the use of the improved soap:

1.7% of aluminum soap of the No. 6 cut of the distillate of acidsprepared by the oxidation of "sweater oil is added to a non-waxynaphthenic oil obtained from a Coastal crude and having a Sayboltviscosity at 210 F. of 55 seconds and the mixture heated to about 175 to200 F. until complete solution is effected. After standing in storagefor 3 months, the oil shows no haze, gelling or other evidence ofseparation of the soap, but remains clear, bright and of excellentappearance.

This oil was tested for 250 hours operation in a Caterpillar Dieselengine and showed superior performance over blends of aluminumnaphthenate or the aluminum soap of acids derived from the oxidation ofcrude scale wax in the same oil.

In some instances, e. g. in the case of the calcium, magnesium, zinc,manganese and similar soaps, difficulties may be encountered indissolving them in certain mineral lubricating oils. In such cases, ithas been found advantageous to add a solubilizing agent (about 5100% ormore of the weight of the soap added) to prevent gel formation and toovercome other efiects of deficiency in solubility of the soaps. Suchsolubilizers may be free fatty acids, fatty esters, naphthenic acids or,esters, aromatic fatty acids such as phenyl stearic acid or theiresters, organic esters of inorganic acids or aromatic polybasic acids,high molecular weight alcohols, alcohol-esters, alcohol-ethers,ether-esters, and other similar high boiling compounds.

It'will be understood that other addition agentsbesides the aluminumsoaps may be added to the Diesel oils, such as oilness agents, corrosioninhibitors, oxidation inhibitors, extreme pressure agents, thickeners,dyes, etc;

The use of these soaps is not restricted to any particular type ofnon-waxy lubricating oil but is applicable generally to all Diesellubricating fractions whether obtained bythe distillation, cracking,hydrogenation, destructive hydrogenation or other treatment ofpetroleum, coals, tars, shales, lignites or fractions thereof.

This application is a division of application Serial No. 181,374 filedDecember 23, 1937, now Patent 2,227,149, issued December 13, 1940.

This invention is not limited by any theories of the mechanism of thereactions nor by any details which have been given merely for purposesof illustration, but is limited only in and by the followingclaims inwhich it is intended to claim all novelty inherent in the invention.

I claim:

1. A composition comprising a polyvalent metal soap of acids derivedfrom the oxidation of sweater oil.

2. A composition consisting essentially .of a polyvalent metal soap ofacids derived from the oxidation of sweater oil."

3. A composition according to claim 2 in which the soap is prepared froma metal selected from the class consisting of aluminum, calcium, nickel,tin and magnesium.

4. A composition consisting essentially of an aluminum soap of acidsderived from the oxidation of sweater oil.

5. A composition according to claim 2 in which the soap is prepared froman .acid fraction boiling between about C. and 280 C. at 4 mm. ofmercury with steam, obtained from the products of oxidation of sweateroil.

6. A product comprising essentially a polyvalent metal soap of acidsderived from the oxidation of a petroleum hydrocarbon fraction calledsweater oil obtained as described in claim 8.

7. An oil-soluble, polyvalent metal soap of an acid fraction boilingbetween about 150 C. and 280 C. at 4 mm. of mercury with steam andhaving an acid number of about and a saponification number of about 240,said acid fraction being derived by subjecting to oxidation with air ata temperature between about 200 F. and 350 F. in the presence of anoxidation catalyst for a. period of about 2 to 4 hours, a petroleumhydrocarbon fraction called sweater oil obtained as described in claim8. v

8. A productconsisting essentially ,of a polyvalent metal soap of acidsderived by the oxidation of a. petroleum hydrocarbon oil fraction calledsweater oil obtained by sweating oil out of a scale wax to make refinedparaflin wax.

EGER V. MURPHREE.

